tag:blogger.com,1999:blog-3784553273521533552.post1775318018045493590..comments2018-03-04T09:20:21.542+11:00Comments on Casey ex Australia: Mars Society Talk: Confronting the Credibility Gap for Crewed Exploration of MarsCasey Handmerhttps://plus.google.com/105494084231616659850noreply@blogger.comBlogger18125tag:blogger.com,1999:blog-3784553273521533552.post-22432980224307532612016-12-22T08:59:40.774+11:002016-12-22T08:59:40.774+11:00So I spent more time looking at lithobraking as I ...So I spent more time looking at lithobraking as I had not heard that term before. Seems like some people have been having fun simulating this: http://forum.kerbalspaceprogram.com/index.php?/topic/33795-has-anyone-made-a-landing-sledintentionally/&amp;page=2<br /><br />I may just have to get this software and see what kind of ships could be made. I still think a litho-sled could be done. There must be some level of mass large enough to make a sled impact at a shallow angle possible. We see this in xtreme sports all the time.<br /><br />Maybe the way a golf-ball rotating before it hits the ground could help lessen the touching down impact.Cloudhttps://www.blogger.com/profile/09477831489975431182noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-20068067870552633622016-12-22T07:50:53.468+11:002016-12-22T07:50:53.468+11:00Thanks for the detailed response.
I still see pot...Thanks for the detailed response. <br />I still see potential here and have some questions... <br />What materials were used for the wheels on curiosity?<br />How big are the rocks?<br /><br />Does the container have to be entirely pressurized?<br />Can the contents not be packed tightly in containers that need to be sealed while the remaining vessel is open to the atmosphere?<br />Cloudhttps://www.blogger.com/profile/09477831489975431182noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-53593310348159338132016-12-22T04:11:28.686+11:002016-12-22T04:11:28.686+11:00Lithobraking (high speed impact) is a thing, but i...Lithobraking (high speed impact) is a thing, but it doesn&#39;t scale well.<br />For comparison, check out videos of airliners landing with wheels up. Or planes landing on water. Both runways and water are smoother than Mars, and stuff still gets messed up, especially when it&#39;s a pressure vessel. <br />Assuming the liftiest of lifting bodies, impact speed is still supersonic, and body drag will torque the vehicle so it tumbles, cartwheels, and generally causes real trouble.<br />One other thing, what looks smooth on a large scale is rarely smooth on a small scale, especially on Mars. Curiosity was deliberately landed in one of the smoothest regions of Mars, and the rocks are so sharp and hard they broke the wheels moving at about 0.03m/s, let alone 600m/s. <br />Some designs call for landing pads or runways, but runways are really annoying. You still have to land the bulldozer, so there&#39;s a chicken and egg problem, and glided approaches are very committing. Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-26737101345611659332016-12-22T04:06:56.849+11:002016-12-22T04:06:56.849+11:00Thank you! Here&#39;s my opinion:
One-way trips ar...Thank you! Here&#39;s my opinion:<br />One-way trips are silly. We need the rocket back for one thing, it&#39;s really expensive and hard to make. <br />I don&#39;t think it&#39;s a safe assumption that we&#39;ll ever have total social/political/psych approval to put humans on Mars with no means of return, at least until there&#39;s tens of thousands of people there. So the question is how to get to the first 10,000?<br />Technology exists, but it&#39;s low TRL. Logistics is a challenge for sustained Earth-supported occupation of Mars. I talk about this in the later chapters of the book. =DCasey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-27503528789162252352016-12-22T03:33:15.724+11:002016-12-22T03:33:15.724+11:00I know nothing about the surface of mars, hopefull...I know nothing about the surface of mars, hopefully it is sandy. If not one would have to get a tractor out there and groom a crazy large sandbox for this. So having said that, what about a trajectory landing using the mars topology like a kid sliding down a slide and landing on his butt. The touch down would be on inclined land and the slide landing(falling on one&#39;s butt) would be lessened by the slide being at ground level. Then speed would be lessened by sliding along soft ground that gives way like sand. <br />Big heavy unmanned landings could use this space troglodyte approach and people could land in small shuttles. <br /><br />The trajectory would require the big heavy thing to first aim for orbit as a holding pattern then drop into the atmosphere at the right time to keep circling around Mars to scrub speed for the eventual touch down on a slope with smooth ground at high speed and slide along for miles. Would be the biggest toboggan ever(with shocks of course).<br />Depending on the approach, maybe the slopes on the Daedalia Planum could be used. The ground looks smoothest here from what I can see on the US geological survey topo map.<br /><br /> - just a knee-jerk thought especially since there is no weight limit(within astronomical reason) on what you can drop on a planet this way<br /><br />- another thought would be a spherical container ship that rolls down the side of a mountain - same principles as above<br /><br />- clearly there would be some high Gs experienced by the troglodyte method so packing of shipped goods would have to be damn good and structurally capable of dealing with the shocks.Cloudhttps://www.blogger.com/profile/09477831489975431182noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-89551327131533564812016-12-22T03:25:36.324+11:002016-12-22T03:25:36.324+11:00Great analysis, well done! Do you think a no-retur...Great analysis, well done! Do you think a no-return mission is something worth considering? Let&#39;s assume for a moment that we have total social, political, and psychological approval. Where are we as far as technology and logistics for such a thing? Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-31386059060139401662016-12-21T17:56:21.415+11:002016-12-21T17:56:21.415+11:00To your first question, yes. Atmospheric entry bur...To your first question, yes. Atmospheric entry burns off 99% of the kinetic energy. Performing a powered descent from orbit would increase the total weight by a factor of at least 8. <br /><br />To your second question, also a good question. I have no doubt it could be possible to land an astronaut in a vehicle the size of MSL (Curiosity). But if there&#39;s to be a way to fly them home, there&#39;s no way around the need to land 10-100T on the surface, maybe much more. In the second last paragraph, and in the video of the speech towards the end, I address the programmatic risk of leaving a large space station (robotic or otherwise) in orbit. I prefer conops where the whole thing flies to Mars to refuel. Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-87619437626112411062016-12-21T16:20:48.132+11:002016-12-21T16:20:48.132+11:00Regarding the EDL problem, would it be prohibitive...Regarding the EDL problem, would it be prohibitively expensive to use propulsion to slow down before entering the Mars atmosphere? <br /><br />What about robotically building a space station in Mars orbit ahead of time that the astronauts could connect with? From there they could split up into much individual landing capsules (one per astronaut). Would something like that just be way too expensive? Or maybe it&#39;s adds too much complexity and introduces too many extra points of failure?GeorgiaEngineerhttps://www.blogger.com/profile/11129276220075837852noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-38589868313758401652016-12-21T15:41:37.844+11:002016-12-21T15:41:37.844+11:00Poke around some more and find some critical cover...Poke around some more and find some critical coverage. Note that in order to get the paper through peer review the authors had to remove the claim that &quot;it works&quot;.<br />It&#39;s not real. Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-33963431110831617272016-12-21T15:08:07.842+11:002016-12-21T15:08:07.842+11:00If you poke around, you might notice that NASA has...If you poke around, you might notice that NASA has found evidence of the EM drive working, and have released a peer-reviewed paper on it: http://www.sciencealert.com/it-s-official-nasa-s-peer-reviewed-em-drive-paper-has-finally-been-published<br /><br />So it&#39;s possible it does work, instead of being impossible.Ernie Parkehttps://www.blogger.com/profile/04863844172900740017noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-44062242015806327102016-10-23T10:35:02.114+11:002016-10-23T10:35:02.114+11:00All good points. I have a detailed blog on the Spa...All good points. I have a detailed blog on the SpaceX ITA as well, I look forward to your thoughts. <br /><br />http://caseyexaustralia.blogspot.com/2016/09/spacex-mars-plan-analysis.html<br /><br />I don&#39;t think SpaceX has all the data they need on Mars, hence the Red Dragon program.Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-75247258501655880502016-10-23T10:29:53.072+11:002016-10-23T10:29:53.072+11:00Yes, this is always an option. Potential issues in...Yes, this is always an option. Potential issues include heat soak, thermal cycling, and uncertainty in atmospheric conditions leading to guidance problems. <br /><br />Also, you&#39;ll need an elliptical orbit. Parabolic and hyperbolic are still escape trajectories. Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-27809199793682502062016-10-23T10:25:47.036+11:002016-10-23T10:25:47.036+11:00Probably not but it&#39;s worth studying, in a suf...Probably not but it&#39;s worth studying, in a sufficiently rigorous, detached manner. Humans have certainly survived outrageous hardship. But it&#39;s worth remembering that, eg, &gt;85% of Magellan&#39;s crew died en route. There are documented cases of mental as well as physical health problems throughout the history of exploration. There&#39;s no need to repeat mistakes of the past. Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-43026492996195952062016-10-23T10:22:45.011+11:002016-10-23T10:22:45.011+11:00Thank you! Thank you! Casey Handmerhttps://www.blogger.com/profile/10894614796135316267noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-75969344293708997132016-10-23T02:44:03.498+11:002016-10-23T02:44:03.498+11:00Has EDL been solved by SpaceX? They&#39;ve tested...Has EDL been solved by SpaceX? They&#39;ve tested much of the profile with Falcon 9 return flights, and Musk&#39;s presentation (made after this text, I believe) show&#39;s what are obviously 3D dynamic flow models. NASA Langley also presents the Hercules architectures, that essentially uses supersonic retropropulsion only, no parachutes. ISRU is the answer to the return problem, as Zubrin has proposed for decades, and it&#39;s the focus of the SpaceX plans for Mars. It&#39;s one of the four elements of the ITS architecture, after all.<br /><br />The credibility gap is more at the level of financing, I find, where politicians and advocates have been unable to overcome the cost/benefit question. Human Mars missions are never cheap enough, as no immediate return is ever possible. And robots can do most of the science. So the justification needs to lie elsewhere.Michelhttps://www.blogger.com/profile/01405756533437775173noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-39395796500401184322016-10-23T02:04:16.992+11:002016-10-23T02:04:16.992+11:00Have there been proposals to slow down by passing ...Have there been proposals to slow down by passing through the Mars atmosphere multiple times? During a first pass, one only has to go from escape velocity to the velocity of some hyperbolic orbit.ant6nhttps://www.blogger.com/profile/04845727393148967959noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-31079515245254974592016-10-22T22:07:42.370+11:002016-10-22T22:07:42.370+11:00I get a bit sceptical about the suggestion that th...I get a bit sceptical about the suggestion that there are novel psychological problems arising from long voyages with cramped space, Look at what people such as Magellan, Drake, Anson, and Cook did, without radio or accurate maps.<br /><br />There are differences. There are ways of getting away from other people on one of those old sailing ships. They could put into shore for a few days. But there were sailing ships that sailed non-stop from Australia to Falmouth without radio. They key term was &quot;Falmouth for orders&quot;, where they would learn where the cargo of grain would be delivered.<br /><br />No, it isn&#39;t the same, but it is still within living memory. Have people changed so much that they would go crazy, in a tin can with radio?zhochakahttps://www.blogger.com/profile/06653786360841345602noreply@blogger.comtag:blogger.com,1999:blog-3784553273521533552.post-80487338742810978632016-10-22T11:43:24.255+11:002016-10-22T11:43:24.255+11:00An excellent post. CheersAn excellent post. CheersRobert F Sullivanhttps://www.blogger.com/profile/05381910947829263643noreply@blogger.com